Both epidemiological and laboratory research are integrated to investigate human health effects of environmental agents. Studies continue to be concentrated in several areas: low-level, long-term exposure to xenobiotics; multiple factor interaction of environmental agents; environmental cancer; asbestos-associated disease; biological effects of inorganic microparticles; halogenated aromatic hydrocarbons (including polychlorinated biphenyls, polybrominated biphenyls, pentachlorophenols, dioxins, dibenzofurans, etc.). In addition, other occupational hazards (particularly work accidents) are being investigated to seek additional information concerning possibilities of prevention. During 1980-1981, a significant extension of the research programs will take place, in the preparation of a prospective pair of surveillance programs of two groups at very high risk of development of cancer; asbestos insulation workers and roofing workers exposed to complex polycyclic aromatic hydrocarbons. Clinical examinations to be undertaken at a variety of sites in the United States will establish baseline observations, including those associated with what may be predictive biological markers, for subsequent prospective observation. Agents being investigated include titanium, lead, fluorine, polychlorinated biphenyls, polybrominated biphenyls, nitrosamines, dioxins, asbestos, nickel, cadmium, vinyl chloride, zeolites, and solvents.